I have a bonded pair: female lop (spayed) 2.5 years old and a small Rex mix (neutered) 1.5 years old.  These two are in their X-Pen during the day and roam most of the house when I am home at night and weekends.  I was offered a 3 month old female Flemish Giant (too young to spay) and when I went to pick her up there was a 9 month old (not spayed) female in the small cage with her.  The owners did not want her and since the two rabbits were already together I took both.

I have expanded my X-Pen so there is a shared X-Pen wall and hard sheet of thick, semi-opaque plastic between the two pens, but when my sweet lop is allowed out to roam the house she goes to the newcomers pen and attacks the older Flemish Giant through the uncovered area (clawing and biting between the bars).  

I am having the older Flemish Giant spayed in three days, but I understand that it will take 4 – 6 weeks for her hormones to die down.  Should I moved the two new bunnies to another room (the 3 and 9 month old Flemish Giants) for another month?  If so, the younger will be ready to be spayed.   I think I am in for a lot of trouble for the next 6 months at least.  The bonded f/m are now peeing outside their litter box to add to the problems.

Any recommendations on how to house these indoor bunnies and for how long before an attempt to bond the two pairs together or even have them near each other?  Hopefully, the youngest female will still get along with the older female and remain bonded as they grow and are spayed, but that is another issue that I cannot worry about yet.